The unexamined patent application DE 10 2004 062 021 A1 shows a system for using free parking spots.
The unexamined patent application DE 10 2008 028 550 A2 shows a parking guidance system for navigating a parking space searching vehicle to a free parking space.
The unexamined patent application DE 10 2009 028 024 A2 shows a parking guidance system for navigating a parking space searching vehicle to a free parking space.